class_docstr: The base class for the metrics configuration.
  
  It determines the step or time range that needs to be
  profiled and validates the input value pairs. Available profiling range parameter pairs are
  (**start_step** and **num_steps**) and (**start_unix_time** and **duration**).
  The two parameter pairs are mutually exclusive, and this class validates
  if one of the two pairs is used. If both pairs are specified, a
  FOUND_BOTH_STEP_AND_TIME_FIELDS error occurs.
docstr: Convert this metrics configuration to dictionary formatted as a string.
  
  Calling eval on the
  return value is the same as calling _to_json directly.
  
  Returns:
      str: This metrics configuration as a dictionary and formatted as a string.
docstr_tok: ["Convert","this","metrics","configuration","to","dictionary","formatted","as","a","string",".","Calling","eval","on","the","return","value","is","the","same","as","calling","_to_json","directly",".","Returns",":","str",":","This","metrics","configuration","as","a","dictionary","and","formatted","as","a","string","."]
code: def to_json_string(self):
      """Convert this metrics configuration to dictionary formatted as a string.
  
      Calling eval on the
      return value is the same as calling _to_json directly.
  
      Returns:
          str: This metrics configuration as a dictionary and formatted as a string.
  
      """
      return convert_json_config_to_string(self._to_json())
  
imports: from __future__ import absolute_import
  from sagemaker.debugger.profiler_constants import DATALOADER_PROFILING_CONFIG_NAME, DATALOADER_PROFILING_START_STEP_DEFAULT, DETAILED_PROFILING_CONFIG_NAME, DETAILED_PROFILING_START_STEP_DEFAULT, SMDATAPARALLEL_PROFILING_CONFIG_NAME, SMDATAPARALLEL_PROFILING_START_STEP_DEFAULT, HOROVOD_PROFILING_CONFIG_NAME, HOROVOD_PROFILING_START_STEP_DEFAULT, PROFILING_NUM_STEPS_DEFAULT, PYTHON_PROFILING_CONFIG_NAME, PYTHON_PROFILING_NUM_STEPS_DEFAULT, PYTHON_PROFILING_START_STEP_DEFAULT, START_STEP_DEFAULT
  from sagemaker.debugger.utils import convert_json_config_to_string, cProfileTimer, is_valid_regex, is_valid_unix_time, ErrorMessages, PythonProfiler
label_desc: Use image node_id 3 for calling the MetricsConfigBase obj's underlying member method code with example usage: obj.to_json_string() and returns: convert_json_config_to_string